Coercivity Enhancement in Sintered Nd-Fe-B Magnets By Dy Diffusion Using Simple Vapor Deposition Technique

We report here the coercivity (H-c) enhancement by way of surface diffusing Dy into the sintered Nd-Fe-B magnets, employing a novel and simple vapor deposition method. The beneficial effect on coercivity and the ominous effect on remanence were both studied and correlated with the time dependent Dy diffusion. The coercivity of Nd-Fe-B magnet is improved by partial substitution of Dy for Nd and described here is the surface diffusion method adopted to infiltrate Dy in to the sintered Nd-Fe-B magnet and the consequential effect on the microstructure and the magnetic properties. An 80% improvement in Hc occurred for four hours of Dy diffusion, while encountering a fall of about 11% in remanence. The SEM-EDS analysis brought out that Dy partition to a higher degree in to the Nd-rich grain boundary phase than the matrix Nd2Fe14B.